Failover and failback policies may be configured in a cluster environment, such as a Microsoft® Cluster Service (MSCS) environment, to ensure high availability of the hosted application and services. Failover clusters provide high availability and scalability to server workloads. These may include server applications such as Microsoft® Exchange Server, Hyper-V®, Microsoft SQL Server® and file servers.
In a failover cluster, if one or more of the clustered servers (nodes) fails, other nodes begin to provide service (a process known as failover). In addition, the clustered roles/services are proactively monitored to verify that they are working properly. If they are not working, they restart or move to another node. Failover clusters also provide Cluster Shared Volume (CSV) functionality that provides a consistent, distributed namespace that clustered roles can use to access shared storage from all nodes.
If the customer has configured failback, the cluster services are moved back to the original node when it becomes active again.
When backup is performed on the virtual cluster node, the backup of the shared disk typically will be performed through the current active node in the cluster. For example, a virtual shadow copy service (VSS) or other snapshot may be taken and used to back up the virtual resource, such as a CSV volume. In prior approaches, the snapshot was not stored persistently. In such approaches, during a failover or failback the backup is interrupted and the VSS snapshot created for the shared disk typically is lost. If configured to do so, the backup solution (e.g., EMC® Networker®) will restart the backup again from the failover node. The process of creating a new VSS snapshot of the shared disk and performing backup will be repeated all over again.